Which isn't, you'll notice, quite the same thing as saying sorry for the study itself.

Speaking to a conference for small businesses in New Delhi, Facebook's Chief Operating Officer did not apologise for the study but did say: “This was part of ongoing research companies do to test different products, and that was what it was; it was poorly communicated."

The study in question saw Facebook altering over 700,000 people's timelines to show either mostly positive or negative posts in their timeline and then seeing whether that would affect the type of content user's would share.

Lasting a week, the study was designed to analyse the 'emotional contagion' affect which suggests that if you see lots of positivity around you it'll 'rub off' causing you to feel more positive and vice versa.

The research was carried out by the Data Science team at Facebook, a small group of researchers who have complete access to Facebook's billions of users.

How? Well when you sign up to Facebook you actually agree to let the company carry out research to improve its services, allowing the company to legally carry out these tests.

In an interview with the Wall Street Journal, ex-Data Science researcher Andrew Ledvina revealed that the team was constantly carrying out research of this nature saying, "Anyone on that team could run a test, they're always trying to alter peoples' behavior."

Whilst social studies are nothing new, the fact that Facebook didn't ask for consent has cause privacy activists to voice their concerns.

In an effort to try and stall the fallout Sandberg gave an interview on New Delhi TV apologising for not communicating with users about the study.

She isn't the only one trying to stem the fallout, one of the study's creators Adam Kramer took to Facebook to try and explain why they ran the experiment.

"The reason we did this research is because we care about the emotional impact of Facebook and the people that use our product."

"We felt that it was important to investigate the common worry that seeing friends post positive content leads to people feeling negative or left out. At the same time, we were concerned that exposure to friends' negativity might lead people to avoid visiting Facebook. We didn't clearly state our motivations in the paper."

Kramer goes on to point out that actually, "In hindsight, the research benefits of the paper may not have justified all of this anxiety."